Ray Optics
Optics Mirrors Laws of Reflection Spherical Mirror A spherical mirror is a curved reflecting surface . It is painted with silver coating on one side , so that it reflects light that is incident on it . The reflected ray always passes through the focus , because the mirror is curved . F = R/2 ; where F is the focus & R is the radius of Curvature . Concave Mirror Convex Mirror Mirror Formula 1/f = 1/u + 1/v Sign Conventions : Follow the cartesian system ; Pole at the Origin ; Distances to the left and bottom will be negative and distances to the right and top will be positive . Lenses Lenses are curved Refracting Surfaces . The refraction takes place such that the refracted ray always passes through the primary focus , since the lens is curved . Concave Lens Convex Lens Plano Convex & Concave Lenses : These lenses have only one hemispherical Surface . Lens Formula 1/f = 1/v - 1/u Sign Conventions : Follow the cartesian system ; optical center at the Origin ; Distances to the left and bottom will be negative and distances to the right and top will be positive . Lens Maker's Equation 1/f = (μ2 - 1)[ 1/R1 - 1/R2 ] Where R1 and R2 are radius of curvatures of the two surfaces . For Plano Convex lens , one surface is straight , thus Radius of curvature for on surface is infinity . Magnification Magnification = h2/h1 = v/u Power of Lens Power of Lens = 1 / f Power of lens is measured in Dioptres , if the focal length is in metres . Vision Correction Myopia Myopia is near Sightedness . A concave lens of suitable focal length is used for vision correction . Hypermetropia Hypermetropia is far sightedness . A convex lens of suitable focal length is used for vision correction . Presbyopia Presbyopia is the condition of weak eye sight for distant as well as for nearby objects . A bifocal lens is used for vision correction . Concept of Conjugate Foci Combination of thin lenses in Contact Optical Instruments Optical instruments are used to either magnify objects nearby or to view distant objects . The arrangement of lenses matters in these instruments . The Distance of Distinct Vision (DDV) is the minimum distance upto which an object can b seen clearly . The DDV is said to be 25 cm . Magnifying Power = Angle subtended at eye by image / angle subtended at eye by object at DDV Simple Microscope Magnifying Power = β/α Magnifying Power = D/v + D/f Thus , magnifying power of Simple Microscope could be anything from D/f to 1 + D/f Compound Microscope Magnifying Power = β/α Magnifying Power = - {vo / uo}{1 + D/fe} Telescope Magnifying Power = - fo/fe Reflecting Telescope Tips And Tricks # The number of images formed by two mirrors inclined at an angle x is 360/x - 1. Category:Physics